81998220 has 48 divisors (see below), whose sum is σ = 239581440. Its totient is φ = 20915136.

The previous prime is 81998219. The next prime is 81998227. The reversal of 81998220 is 2289918.

It is not an unprimeable number, because it can be changed into a prime (81998227) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 28330 + ... + 31089.

It is an arithmetic number, because the mean of its divisors is an integer number (4991280).

Almost surely, 2^81998220 is an apocalyptic number.

It is an amenable number.

81998220 is an abundant number, since it is smaller than the sum of its proper divisors (157583220).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81998220 is a wasteful number, since it uses less digits than its factorization.

81998220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 59454 (or 59452 counting only the distinct ones).

The product of its (nonzero) digits is 20736, while the sum is 39.

The square root of 81998220 is about 9055.2868535458. The cubic root of 81998220 is about 434.4450049862.

The spelling of 81998220 in words is "eighty-one million, nine hundred ninety-eight thousand, two hundred twenty".